fixed

固定显示：

$(window).scroll(function(){
            rightScroll();
        });
        function rightScroll(){
            var wH = $(window).height(),
                    eH = $("#float").height(),
                    sH = $(window).scrollTop();
            $("#float").animate({top : (wH-eH)/2+sH+50},{ queue: false, duration: 900 });
        };